A navy ship doesn't deserve to survive because of the sentimentality of its crew. The military is a rough trade. Maybe we don't need to practise beach landings with the United Arab Emirates, send frigates to the Falklands, do anything about Libya or retain the capacity to rescue civilians. Maybe what happens in Syria is none of our business.

But to the extent that we think some of this matters, we do need armed forces. Our defence choices come down to being able to blow the world to Armageddon with Trident, being able to send in an army when the last thing any politician wants to justify is putting boots on the ground, or doing nothing.